Sunday, November 4, 2018

The EFHW-8010 End Fed antenna was recommended so we gave it a go. The installation has the "business" end of the 130 feet antenna wire about 50 feet high
sloping down to about 8 feet with some para-cord support from an overhanging tree near
mid run to keep the antenna wire high as long as possible. The inline choke and and
matching transformer are located in the attic. This is not the optimal
setup, but the configuration was convenient for our QTH. We are very happy with the performance and the Icom IC-7300 tunes it to well to all spec'd bands.

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Once again, my Elmer friend let me borrow an antenna analyzer to test things out. This analyzer is very nice kit with a sturdy case, touch screen interface, and an easy to understand user interface. Go to this page and see the AQRP 8KHz to 440MHz Vector Impedance Analyzer kit #25 for more details. It's well documented and a very slick package.

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Below are the SWR plots and a few Insertion Loss plots for the bands. Remember, the EFHW-8010 End Fed antenna is spec'd from 10m to 80m. We tested it on a few bands outside its design spec. All measurements are made through 50 feet of RG8X, plus 25 feet of BNC cable, plus an Alpha Delta 4:1 coax switch.
-----2 meters:

-----6 meters:

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10 meters:

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12 meters:

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15 meters:

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17 meters:

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20 meters:

-----30 meters:

-----40 meters:

-----60 meters:

----- 80 meters:

-----160 meters:

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Regardless of how you interpret the data the antenna is working well for our setup. 73 and see you on the bands!
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Friday, August 24, 2018

An OFC Dipole antenna was recently paid-forward to me. My Elmer friend let me borrow an antenna analyzer to check it out. I soon learned that the analyzer was actually put together from a kit. It is a very nice package with a sturdy case, touch screen interface, and an easy to understand user interface. Go to this page and see the AQRP 8KHz to 440MHz Vector Impedance Analyzer kit #25 for more details. It's well documented and a very slick package.

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Right away I wanted to play with the analyzer and decided to sweep a few 2m hand held radio antennas as a test (results below).

It's interesting how much flatter the VSWR curve is with the Nogoya NA-771 VHF/UHF aftermarket duckie. Also, I never tuned the DIY 2m Tape Measure Yagi but just following the build instructions carefully seemed to yield good results.
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And, just for grins we swept a DIY simple wire dipole that was cut for 20m which is only use for Rx with a SDRPlay RSP1A. Our placement for the dipole is marginal and it works equally marginal on 20m and 40m. FWIW, here are the results:

Monday, August 20, 2018

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When learning Morse code (referred to as CW in ham radio circles) a practice oscillator can be helpful. It lets you practice your sending without transmitting. Also, if can be useful if you are wanting to practice sending/receiving CW with another ham through a Skype channel without waiting for propagation conditions. A voice channel like Skype also allows immediate voice feedback for effective Elmering.
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We shelled out $10US on eBay and a few days later we got the practice oscillator pictured above in kit form from Electroresales with some good instructions. After about 30 minutes we had a working (and very loud if you crank the volume) practice oscillator. We made one small mod by adding a JST connector in parallel to the power barrel jack. This made it easier (for us anyway) to connect a 9VDC battery without having to find the right size barrel jack connector to supply the power.
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The result:

Saturday, June 16, 2018

----CQ CQ CQ.... In the "olden" days, Morse Code (or CW) was a requirement for a Ham Radio license. That is no longer the case, but for some reason CW seems to have a new interest with those in the hobby. After seeing more and more discussions about CW we decided to give it a try.
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Three things are needed:
1) An FCC Amateur Radio license; it's not hard get and it is an extremely interesting hobby.
2) A radio that can transmit/receive CW signals. We chose the QRP Labs QCX Kit.
3) You have to know Morse Code; how to send it and how to decode it.

The first two are easy. The third one not so much, but there are a host of tools and advise on the web to help. Just search google. We have only been at it 30 days and show progress, but still have a long way to go.
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Back to the QCX kit.... We wanted something cheap, small, and portable. We read great reviews about QRP Labs QCX Kit and decided to give it a go. After asking around about the best band for CW newbies we decided to configure for 40 meters. This page was originally going to document the build process, but really there is no need. The instructions and documentation provided with the kit are AMAZING. Really, they are! Great images, diagrams, etc. There are lots of solder joints and some toroids to hand wind, but follow the directions exactly and you will be fine.
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Here is the whole enchilada in a niffy 3D printed case purchased from W4KHZ / Mike. At $25 shipped it is a great value.

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And... a low cost transceiver is of no use without a low cost antenna. We had spare long runs of common speaker wire and hand cut a dipole for 7.050MHz (a common frequency for 40m CW). We must have been using calibrated wire cutters. Below is the initial SWR sweep from 7.000MHz to 7.100MHz.

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All in all we are very pleased. Now back to CW practice. Thanks for the visit and maybe we will hook up on 40m.

Thursday, April 12, 2018

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From time to time the International Space Station (ISS) will activate their Slow Scan Television (SSTV) transmitter. April 12, 2018 was one of those times as the Russian crew commemorated Cosmonautics Day. Getting a SSTV image from the ISS is kind of like getting a FAX sent to you from a spaceship. In the case of the captured image above the ISS was transmitting an audio signal to Earth on a frequency 145.800MHz with 25 Watts. The signal is strong and lets anyone with some basic equipment receive and decode the image.
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For this capture we used:
- The Heavens Above website to predict the ISS pass.
- A Kenwood TH-D72A to receive the signal (could be a low cost ham radio or SDR).
- A DIY Yagi antenna (the signal was so strong this was probably not required).
- A small recorder to save the audio received.
- Software to decode the recorded audio into an image. We used RX-SSTV.
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The whole process takes some planning and setup, but it's not that hard and it was rewarding to see the result. If you want to hear what our image "sounds like" or test your decode SW then play this:

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Later that evening I was able to downlink these two images in one pass:

Sunday, March 25, 2018

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Note: As presented this project requires a FCC Amateur Radio license. Amateur Radio is about experimentation. Even still you must be versed in the band plan and stay away from local repeater stations, stay in accordance to FCC Amateur Radio rules such as 97.201(a), 97.201(b), 97.213(a), 97.215, 97.3(a)(7), and likely a few others. Even after following all those rules, nobody likes to hear a bunch on random DTMF tones so keep your transmissions short and infrequent.
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Most Amateur (or ham) radio operators have wondered how or if their signal is getting received. After getting a YES/NO answer they may want to decrease power, try a different antenna set up, or change location. The challenge with this can be a willing participant on the receive side that has promised to remain perfectly still and listen for hours. If you have a friend or XYL willing to do that then consider yourself fortunate. For all the others there is this project.
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The rig is pretty straight forward and explained in the image above.
- From the field a DTMF tone is transmitted on a frequency that "the shack" is tuned to.
- If the radio in the shack hears the DTMF tone it is decoded with this module.
- Code running on an ESP8266 turns the decoded tone "to English" and sends a SMS text message via IFTTT.
- If the shack received everything you will get a confirming QSL SMS on your smartphone.
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It's all quick and simple. It takes only a 250 mSec or so transmission time and a delay of maybe 2 seconds to get the confirming QSL SMS. The short video below gives a good explanation:

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Want to build your own? No problem.
1st: Get a FCC Amateur Radio license; it's not hard and is an extremely interesting hobby.
2nd: Buy some radios (costs range from $30 to infinity).
3rd: Buy the DTMF module and an ESP8266.
4th: Set up a free IFTTT account for the SMS texting.
5th: Hook it all up as shown in the image at the top of this page.
6th: Load the source code below into your ESP8266 (you will need the Arduino IDE).
7th: Be respectful of the rules and test away.
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Before showing the ESP8266 source code here's a short video using 5 of the 8 channels on the Tektronix MSO5 (which is bad ass!!!) to monitor the signals coming off the DTMF module.

// Program control variables
int logging = 1; // If 1 then send SMS. Any other value (0) turns it off. For debug, typically would be set = 1

void setup(void){ // This setup code is run once.
pinMode(led, OUTPUT); // set up the onboard Blue LED pin as an output.
pinMode(Q1, INPUT); // Q1-4 are the output signals from the DTFM IC
pinMode(Q2, INPUT); // that are feed into and read by the ESP8266
pinMode(Q3, INPUT);
pinMode(Q4, INPUT);
pinMode(STQ, INPUT); // STQ is high when DTFM tone is detected

// The blue onboard LED will blink between to show prog is 'running'.
digitalWrite(led, !digitalRead(led)); // toggle state of the on board blue LED.

if (digitalRead(STQ) == HIGH) { // If it HIGH then DTFM detected. Let's get to work.
Serial.println("DTMF Detected!!!");
DTMF_String = "Could_not_decode_DTFM!"; // Should be overwritten below, but just in case Mr Murphry shows up...

Sunday, January 28, 2018

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It's done everyday, but (as they say) you never forget your first. The 'cube' above is Satellite A0-91. This little guy has a VHF/UHF amateur radio repeater on board which means it is available for use if you hold a FCC Technician license.

It's not overly difficult, but it is a good challenge. Today we were able to get a contact for the first time. It's pretty satisfying using a $50'ish handheld radio to communicate via space.
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Here is the audio: